As a communication system for communication between a communication terminal apparatus and a base station apparatus, disclosed in Patent Document 1 is a communication system to control power supply in a relay apparatus (base station, station) having a plurality of interfaces. In the case of controlling power supply in a relay apparatus having a plurality of interfaces, although a wired interface (IEEE (Institute Electrical and Electronics Engineers) 1394) and a wireless interface of the relay apparatus of the conventional art have a wired standby means and a wireless standby means respectively, there is no comprehensive power control method and thus controlling the power supply may cause waste of standby power and inefficiency in power management to shift to and recovery from a power save mode. In order to solve such a problem, the communication system disclosed in Patent Document 1 recovers one relay apparatus in a standby state in the power save mode by transmitting a recovery instruction to the relay apparatus from the other relay apparatus.
Further, disclosed in Patent Document 2 is a communication system to call a mobile terminal using different communication systems of PHS (Personal Handyphone System) and a wireless LAN (Local Area Network) of IEEE802.11b standard by use of PHS paging function that requires less power consumption, when the wireless LAN is not enabled. This communication system disclosed in Patent Document 2 reduces power consumption of the mobile terminal by performing paging with the PHS.
In addition, Patent Document 3 discloses a communication system in which, when a multimedia terminal apparatus transmits a packet signal to a wireless mobile terminal in power save mode via a wireless base station, the wireless base station temporarily stores the packet signal, and transmits broadcast information to the wireless mobile terminal by periods. Then the wireless mobile terminal in power save mode analyzes the broadcast information, thus knows whether the packet signal addressed to the own terminal is temporarily stored in the wireless base station and requires transmission of the packet signal to the wireless base station if stored.
In the communication system disclosed in Patent Document 3, the wireless mobile terminal determines whether realtime communication is necessary based on a protocol part of a packet signal when receiving the packet signal that the wireless mobile terminal has requested to transmit from the wireless base station. When it is determined that the realtime communication is necessary, the wireless mobile terminal notifies the wireless base station of its shift from the power save mode to a normal mode, and notifies the wireless base station of its recovery to the power save mode when the realtime communication is finished.
Incidentally, a sleep mode is defined for a mobile terminal in IEEE802.16-2005. In the sleep mode the mobile terminal apparatus turns off the power supply to the wireless circuit unit intermittently to save the power. In addition, unlike the mobile terminal apparatuses of the conventional arts, the mobile terminal apparatus in conformity with IEEE802.16 standard can establish a plurality of logical connections with a single base station.    Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-007187    Patent Document 2: Japanese Patent Laid-Open Publication No. 2003-229800    Patent Document 3: Japanese Patent Laid-Open Publication No. 2004-172772